The present invention is directed to refrigeration systems and methods in which a cooling effect is provided by an isenthalpic pressure drop between isolated volumes. The expansion occurs as part of a vapor compression and expansion cycle. However, the expansion process through an orifice (also referred to herein as a channel) can suffer from reliability problems. In particular, refrigeration systems using a vapor compression and expansion cycle are susceptible to fouling failures which occur at the expansion device (that is, at the isenthalpic pressure drop point). The expansion devices in prior systems typically include capillary tubes and fixed sized orifices which do not provide any (thermal) control. Other expansion devices include expansion valves in which some valves are controlled via a pressure bulb or via electrical means (such as with a stepper motor). All of these devices require small geometries to accomplish the desired refrigeration expansion or pressure drop. It is at this large pressure drop point with commensurate temperature change which particularly causes impurities to precipitate out and to be deposited on the expansion device's small geometry. Fouling or accumulation of impurities at the expansion device can therefore cause poor performance and even outright failure of the refrigerant cycle.